Trench gap-filling copper by ion beam sputter deposition

The ion beam sputter deposition (IBSD) and electroless plating techniques have been combined to achieve the precipitation of Cu onto an amorphous (a)-TaN diffusion barrier layer in order to accomplish the ultralarge-scale-integrated interconnect metallization. The copper-filled specimens were annealed at various temperatures in a reduced atmosphere. The preferred orientation was analyzed by X-ray diffraction, and field emission scanning electron microscopy was used to elucidate the growth mechanism of the trench-filled electroless deposited Cu film on the Cu seeded layer by IBSD. The Cu(1 1 1) texture was strengthened by annealing at 300 °C for 1 h. The surface roughness increased notably with increasing annealing temperature. The electrical resistivity of the as-deposited copper film (3.05 μΩ cm) decreased with increasing annealing temperature. The major contribution of this study is to successfully combine the techniques of IBSD and electroless plating for the Cu gap-filling of submicron trenches with an excellent step coverage.